My airbags haven't deployed yet and I have been using my Katana (an unapproved cellular phone). I peeled a sticker off the upper left corner of my windshield that was annoying me. It reads:

Important: Installation and operation of non-BMW approved accessories such as alarms, radios, amplifiers, radar detectors, tires, wheels, suspension compoenents, brake dust shields, telephones (including operation of any portable cellular phone from within the vehicle without using an externally mounted antenna) or transceiver equipment (eg. C.B., walkie-talkie, ham radio or similar) may cause extensive damage to the vehicle, compromise its safety, interfere with the vehicles's electrical system or affect the validity of the BMW Limited Warranty. Refer to your Owner's Manual and see your authorized BMW center for additional information.

Do not use key or remote to lock doors or trunk with anyone inside the car. See Owner's Manual for more details.

Use caution whenever moving the driver's seat or closing the windows/sunroof, so that occupants or pets are not trapped.